Conventional surface treatment compositions may include certain cationic polymers and anionic surfactants. The combination of these components in a surface treatment composition can yield benefits to a variety of surfaces, including but not limited to, fabric and hair.
The benefits may be achieved by complexing certain cationic polymers with anionic surfactant to form a precipitate complex, which is known as a “coacervate.” The benefit of the coacervate is many times proportional to the amount of polymer which can be formulated into a surface treatment composition. However, formulating too high a level of polymer in compositions containing anionic surfactant can lead to undesirable phase separations and/or thick, clumpy product when the surface treatment composition is stored over a period of time.
Coacervates may deliver various benefits familiar to one of ordinary skill in the art to surfaces including but not limited to fabrics and hair. Exemplary benefits include, rejuvenation, softening, conditioning, delivery of benefit agents like anti-dandruff actives and silicone emulsions and surface repair. In the laundry context, coacervates may particularly provide for fabric softening. Additionally, coacervates are especially effective at rejuvenating fabric for clothing items that have lost their color and faded over time, a phenomenon which can frustrate consumers.
Without wishing to bound by theory, it is believed that during the laundry wash cycle, coacervates are deposited on the fabric surface and re-set the fibers and/or fibrils. Re-setting the fibers or fibrils is believed to result in smoother yarn, reducing the number of fibers protruding from the fabric surface. Protruding fibers and/or fibrils are able to scatter light, and produce an optical effect of diminished color intensity. Thus, re-setting these fibers and/or fibrils results in less light scattering and a more intense perceived color.
In the context of hair, it is believed that the coacervates may aid in depositing benefit agents to the hair surface, which actives can for example provide for a hair conditioning benefit and/or split end repair. The benefits of the coacervates may be tempered by the formation of a coacervate within the container housing the surface treatment composition. This may in turn yield an undesirable product which is undesirably thick and/or difficult to pour or dispense. Further, settling of a coacervate in the composition could lead to a variable benefit profile across doses as the consumer uses the composition. One way to overcome these formulation issues is to reduce the amount of cationic polymer in a composition to 5% by weight or less such that the undesirable overproduction of coacervate is minimized. However, by minimizing the amount of cationic polymer, the conventional formulations also lose some of the surface treatment benefits achieved when greater amounts of cationic polymer are included.
Recent work described in co-pending U.S. patent application No. 61/558,480 has disclosed the use of shielding salts as a method of electrostatically screening surfactant and polymer from each other as a solution to the aforementioned problem. This work has been described as most effective when the polymer contains a hydrophilic co-monomer in addition to the cationic co-monomer, wherein such hydrophilic co-monomer has a log P or log D below 1. However, this work does not identify a route to stabilize cationic polymers that do not contain a hydrophilic co-monomer. Indeed until now, the cationic polymer poly-DADMAC has been virtually impossible to formulate into fabric care and hair care compositions at the levels described herein.
Thus, there is a need for a surface treatment composition that includes higher levels of both cationic polymer and anionic surfactant to achieve improved surface treatment benefits without yielding undesirable coacervates in the packaged composition.